Explicit secular equation for Scholte waves over a monoclinic crystal

The acoustic waves propagating at a fluid/solid interface were analyzed. The explicit secular equation for Scholte waves over an orthorhombic crystal was established. It was found that the crystal may be a monoclinic crystal with symmetry plane at x³=0, or a rhombic, tetragonal or cubic crystal cut along a plane containing x³, which makes an angleθ≠0 with the other crystallographic planes. Calculations for usual combinations of a solid and a fluid show that the speed of a Scholte wave was very close to the speed of sound in the fluid.